This invention relates to a method of operation for data processing apparatus, and in particular such a method is described which is especially useful in telecommunication switching systems.
Data processing systems are known comprising a plurality of computers, storage units and input/output control units which cooperate with one another. This cooperation is coordinated by automatic control equipment, and the work is distributed according to well-defined rules determining priority. The priority or precedence can be established as a function of the time, external demands, as well as programs and functions of variable conditions. Accordingly, the control equipment causes programs to be run, whereby the completion of programs and conditions for the interruption thereof are taken into consideration (see West German Pat. No. 1,449,532, pp. 1 and 2, claims 4 and 15 and corresponding U.S. Pat. No. 3,419,849). Obviously, during the cooperation of sections of a data processing system there is traffic between the sections with data being transmitted therebetween. It is also well known that traffic and statistical considerations for the convenient construction and dimensioning of such equipment for data processing systems play a part. These matters have already been dealt with, but concrete solutions have not yet been proposed (see "Elektronische Rechenanlagen," 1970 pp. 249 - 252).
If desired, the above mentioned sections of data processors can be combined into various complete data processors which together form the data processing system (see "Elektronik" 1969, pp. 217 - 219). The commands accumulating in such a data processing system can be operated upon in batch processing where, as a first step, they are grouped for processing. In contrast, in real-time processing, each task is processed immediately after its appearance. The commands usually do not appear at regular time intervals, but are statistically distributed according to the calculus of probabilities. This must be taken into consideration when designing a real-time data processing system, so that in case of job accumulation the response time will not be exceeded (see Lobel, Muller, Schmidt: "Lexikon der Datenverarbeitung," second edition, pp. 418, 419, and 482). An overload condition will exist if the response time is exceeded; that is, a data processor becomes loaded with so many tasks that it delays dealing with them for longer than a predetermined time, i.e., it no longer operates in real time. Furthermore, such data processing system can also be operated efficiently, so that the attainable benefits can be taken advantage of. It is not sufficient by means of a control equipment which only considers predetermined priorities or precedences to coordinate the cooperation of the sections pertaining to the data processing system, so that the system will operate efficiently, particularly to avoid delays.